The goal of this project is to study the relationship of neuronal form to function. All projects depend upon computer associated analysis of neuronal morphology (core unit) to aid in this. Specific studies are: (1) To examine the mammalian muscle spindle as a model of localized inputs to a branched neuronal structure (Project 1); (2) To examine amacrine and ganglion cells in the vertebrate retina to evaluate models for neuronal activation (Project 2); and (3) to examine neurons in the mouse cerebral cortex as a model for "mapping" intracortical connectivity (Project 3). In each case the relevant structures are revealed by selective optical and anatomical methods including Nomarski optics, intracellular injection of dyes (Lucifer yellow and HRP), the Golgi method and 3H-2-DG autoradiography. All preparations are analyzed with a computer based image processing system which allows for accurate measurement and display of three dismensional process lengths and the on-line alignment of sequential images for either serial sections on adjacent frames of movie films (core unit). We hope to gain fundamental insites into the details of neuronal form as related to activity and from this to provide a basis of understanding which is a necessary prerequisite for understanding cellular changes which occur in diseases of the nervous system.